create one CmakeList.txt file for multiple subdirectories each containg its own src(.cpp files) and include(.h files)

How to write one Cmake file that compile all my sub-directories each with its own executable?

       /Project
            Cmakelist.txt
            /project 1
                /src
                  .cpp
                /include
                  .h
            /project 2
                /src
                  .cpp
                /include
                  .h